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| Titel |
The Last Interglacial Ocean Circulation: model-data comparison of deep sea δ¹³C and flow speeds. |
| VerfasserIn |
Pepijn Bakker, Aline Govin, David Thornalley, Didier Roche, Hans RENSSEN |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093483
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| Publikation (Nr.) |
 EGU/EGU2014-8249.pdf |
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| Zusammenfassung |
| The Last Interglacial period (LIG) provides an excellent possibility to assess the impact of
future Greenland Ice Sheet (GIS) melt on the Atlantic meridional overturning circulation
(AMOC), as the LIG climate is characterised by warmer than present-day high-latitude
temperatures and a partially melted GIS. For a direct model-data comparison of the
evolution of the AMOC in this palaeoclimatic context, we focus on deep sea δ13C
and flow speeds. Here we present the results of a 12ky transient LIG simulation
with a 3-dimensional global climate model that resolves carbon cycle dynamics
in all compartments of the climate system. Through an idealized GIS melt water
scenario, we force the AMOC to evolve from a shutdown state to a weakened state
and finally a full strength state after the GIS melt forcing is removed. This model
scenario allows us to characterize the simulated evolution of deep sea δ13C and flow
speeds in the Atlantic Basin and compare with proxy-based reconstructions from key
locations.
The simulation reveals large scale correlation patterns between the evolution of
deep sea δ13C on the one hand and the evolution of the AMOC strength and the
Northern and Southern Hemispheres δ13C source region signals on the other hand.
Moreover, these correlation patterns differ with depth and latitude, reflecting the
positioning of the different Atlantic water masses. The simulated evolution of deep
sea flow speeds reveals a much more local character compared to δ13C, with a
strong correlation to the evolution of the AMOC strength in specific regions, like the
deep western boundary current (DWBC), but a local origin in many other regions.
Based on this analysis we perform a model-data comparison of the LIG evolution
of deep sea δ13C and flow speed for key sites around the DWBC. We are able to
show that deep sea δ13C and flow speed reconstructions from such relatively small
regions can differ widely. More importantly, we can connect these variations to
the differential impact of changes in the ratio of northern versus southern sourced
waters, changes in the δ13C source region signals and local, non-climatic features. |
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